After the credits, there is an enjoyable one minute scene with Sharpay and Zeke.

The scene where Troy goes to Gabriella's house and they do the Romeo and Juliet style scene had to be cut short in filming because fireworks were going off at a nearby wedding reception.

In the cafeteria, all the milk cartons had a lemon and lime drink in them. The reason for this is that if they were filled with real milk, it would have turned sour during filming.

In the scene Mrs. Darbus is introduced into the movie, Troy was talking about a "big jelly". At that point, he was told to make anything up in those few seconds.

One of the basketball players (number 44) choreographed all the dances.

In this film (unlike HSM2), Zac Efron's (Troy) singing voice is actually Andrew Seeley's singing. It is Seeley who sings "Get'cha Head in the Game" in its entirety and the reprise of "What I've Been Looking For." The only parts that are actually Zac's vocals are: the first four lines of "Start of Something New," the singing on Gabriella's balcony, and the very first sentence of "Breaking Free." The producers wanted a tenor, which Zac is not.